---
title: "Engineering Expert’s Use of Manual J Fails Daubert Reliability Test"
meta:
  "og:description": "Inconsistent and unsupported assumptions undermined the reliability of the expert testimony, leading to its exclusion under Rule 702"
  "og:title": "Engineering Expert’s Use of Manual J Fails Daubert Reliability Test"
  author: "Expert Witness Profiler"
  description: "Inconsistent and unsupported assumptions undermined the reliability of the expert testimony, leading to its exclusion under Rule 702"
---

# Engineering Expert’s Use of Manual J Fails Daubert Reliability Test

Posted on June 23, 2025 by Expert Witness Profiler

Plaintiff Sheheryar Ahmad sued Defendant Spinnaker Insurance Co., his insurer, for breach of contract based on Defendant’s refusal to cover damages caused by frozen and burst pipes in Ahmad’s home.

The Plaintiff argued that although the insurance policy excluded coverage for damage caused by frozen pipes, his claim qualified for an exception to that exclusion because he had taken “reasonable care to maintain heat” as required by the policy.

Plaintiff’s home consumed seven thermal units of natural gas between December 14, 2022 and January 14, 2023, the period during which the pipes froze and burst.  To establish that seven therms sufficed to maintain reasonable heat, Plaintiff relied on the expert testimony of Dr. [Brian K. Bramel](https://expertwitnessprofiler.com/expert-witness/Brian-Bramel/1565165).

The Defendant, however, filed a request to exclude Bramel’s testimony regarding the home’s internal temperature at the time of the frozen pipes.

## **Engineering Expert Witness**

Dr. [Brian K. Bramel](https://expertwitnessprofiler.com/expert-witness/Brian-Bramel/1565165) is a principal at his own engineering firm and holds undergraduate and graduate degrees in Mechanical and Civil Engineering.

He also serves as an adjunct professor in the Department of Architecture at the University of the District of Columbia.

[Get the full story on challenges to Brian Bramel’s expert opinions and testimony with an in-depth Challenge Study](https://expertwitnessprofiler.com/order/add?eId=1565165&amp;pId=3).

## **Discussion by the Court**

Bramel’s report applied the Manual J calculation, a standard thermodynamics methodology generally used to size heating equipment and developed by the Air Conditioning Contractors of America (ACCA) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

In its ordinary function for equipment sizing, Manual J is used to “determine the therms necessary in order to reach a chosen temperature inside a structure.”

However, per Bramel, the methodology can be used “in reverse,” using basic algebra, to determine the interior temperature based on measurements of the “features of the subject premises” and total energy used in this context. 

#### **_Bramel’s Application of the Manual J Calculation_**

The Manual J calculation determines “the energy required for a house based on the interior and exterior temperature differences.” A key element of the calculation is the “resistance factor” of the structural elements in Plaintiff’s home, which refers to the energy lost through the walls, floor, roof, and windows.

Under the equation, the total “energy input to the building from the gas and electric” is equal to the “thermal resistance of the assembly” multiplied by the “area” of the resistance and the difference between the outdoor and indoor temperatures. 

Bramel summarized the equation as follows: _Q<sub>in</sub> = U A (t<sub>inside</sub> – t<sub>outside</sub>)_, where _Q<sub>in</sub>_ refers to the “energy input to the building from the gas and electric,” _U_ refers to “thermal resistance of the [structural] assembly,” _A_ refers to “area” of the resistance, and _(t<sub>inside</sub> – t<sub>outside</sub>)_ refers to the temperatures inside and outside, respectively.

#### **_Reliability of Bramel’s Methodology_**

The Defendant contended that Bramel’s testimony should be excluded because he had inappropriately repurposed a well-established methodology—typically used for sizing heating equipment—and applied it to a completely different context. While there was no dispute that Manual J is a reliable method for determining appropriate equipment size, the Court found that the Plaintiff failed to show it was suitable for use outside of that context, particularly for calculating internal temperatures in reverse.

Bramel himself acknowledged during both his deposition and live testimony that he was unaware of any scientific or engineering publications endorsing this reverse application of the method. He claimed the approach remained reliable because it involved basic algebra applied to standard thermodynamic principles. However, the Court concluded that Bramel’s modification of the Manual J methodology significantly weakened his argument, as altering a known calculation for a novel use called into question its scientific reliability.

Bramel’s hypothesis was not only untested but, by his own admission, untestable. The Plaintiff failed to present any evidence showing that Bramel’s method had ever undergone testing. During the evidentiary hearing, when questioned about whether his methodology had been tested, Bramel merely asserted that it was valid—offering no data or studies to support that claim. Furthermore, he acknowledged that a key component of his analysis—the calculation of total “internal gains”—could not be tested, as it was based on what he described as “a reasonable guess” grounded in an “engineering assumption.”

#### **_Application of Methodology to the Facts_**

The Court found that Bramel’s use of the Manual J methodology failed to meet the reliability standards required under _[Daubert](https://www.law.cornell.edu/wex/daubert_standard)_ and [Rule 702](https://www.law.cornell.edu/rules/fre/rule_702#:~:text=Rule%20702%20sets%20forth%20the,is%20a%20relatively%20narrow%20inquiry.). It pointed to multiple instances where Bramel relied on inconsistent and unsupported assumptions, all of which significantly weakened the credibility of his testimony.

First, Bramel did not provide a clear or consistent justification for overriding Manual J’s default outdoor temperature value of 14 degrees Fahrenheit. From the beginning, he struggled to explain the meaning of the “outdoor 99% db” variable used in Manual J. During his deposition, he spent more than ten transcript pages attempting to respond to defense counsel’s questions on the topic but failed to articulate a coherent understanding. Despite this, Bramel replaced the preset value with his own figure of 33 degrees Fahrenheit, yet he was unable to offer a satisfactory explanation for making that manual override.

Second, Bramel’s report offered neither a rationale for considering the additional variable of “internal gains” in his calculation nor an explanation of how he reached his ultimate assumed value.

Third, Bramel’s assumptions about the structure of the Plaintiff’s home conflicted with the actual facts. He classified the home as “tight,” a designation in Manual J reserved for structures that are “sealed by meticulous workmanship” and exhibit the “lowest level of air leakage.” However, Bramel admitted during both his deposition and the hearing that industry standards require the use of “blower door tests” to assess a home’s tightness. He conducted no such test in this case, undermining the credibility of his classification.

Furthermore, Bramel’s analysis assumes Plaintiffs home comprises one window, despite both photographs and inspections “revealing the house had 10 times that many windows.”

## **Held**

The Court granted Defendant’s request to exclude the testimony of Dr. Brian K. Bramel.

## **Key Takeaways:**

- If the Court, or any other experts, cannot test a critical assumption in Bramel’s methodology, then there is no “objective basis” to test the reliability of the methodology overall.

- The cumulation of errors, inconsistencies, and absence of support render Bramel’s analysis entirely unreliable under Rule 702.

## **Case Details:**

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